Are there undiscovered people?

According to Survival International, the most isolated tribe in the world is the Sentinelese, a group believed to be directly descendent from the first humans to emerge from Africa. For the past 60,000 years or so, they've lived in a remote corner of the Andaman Islands in the Indian Ocean, having so little contact even with other Andaman Islanders that they speak a different language. But the Sentinelese aren't stuck in the Stone Age -- they make tools and weapons from metal, which they recover from shipwrecks. They know about the outside world. They just don't want any part of it. When an aid helicopter flew low over their territory after the 2004 Indian Ocean tsunami, a man rushed out and angrily aimed an arrow at it. The message was clear: Stay away [source: Most Isolated].

It's not that all isolated tribes have tried to escape from civilization. It's just that often the ones who didn't became enslaved or wiped out. It's a tradition that goes back to the venerable Christopher Columbus, whose first thoughts upon encountering the friendly Arawak people in the West Indies was that they would make good servants [source: Columbus]. And we all know what later happened to the Aztecs and Incas and to Native American tribes in the United States after they were contacted by Europeans. And, witness the more recent plight of the Akunzu, a tribe that hunted and grew corn in a remote region of western Brazil for thousands of years, before being discovered in the mid-1980s by homesteaders who wanted the land for soy cultivation and cattle ranches. In 1990, outsiders massacred the entire tribe of several hundred, except for seven who escaped into the forest and hid. In 2009, a newspaper reported that just five of the Akunzu remained alive [source: Adams].

Even when outsiders aren't homicidal, they bring an even bigger threat: microbes for which aboriginal peoples lack immunity. In the late 1980s, for example, after well-meaning Christian missionaries made contact with the Zo'é tribe in Brazil, 45 of the tribe's members promptly died of flu, malaria and respiratory diseases. Fortunately, the Brazilian government expelled the religious group, and the Zo'é gradually went back to their isolated but healthy existence [source: Threats].

So it's not too hard to figure out why an aboriginal group would want to be invisible. The big question is whether they could pull it off.